Doosan G643, Руководство по обслуживанию

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G643 (E) Service Manual Chapter 3. Engine Mechanical System 79
C . Adjust the piston pin installer (J 24086-9) to
the correct length, using the letter-number
scale on the installer adjuster. This is
necessary to ensure that the piston pin is
pressed into the piston to the correct depth.
Refer to the instructions supplied with the tool
for the proper setting.
D . Lock the adjuster in place with the lock ring.
NOTICE: After the installer hub bottoms on the
support assembly, do not exceed 35,000 kPa (5,000
PSI) pressure, as this could cause damage to the
tool.
E . Place the adjuster in the support fixture. Press
the piston pin into place (until the adjustable
installer bottoms in the support fixture).
F . Remove the piston and connecting rod
assembly from the tool and check the piston
for freedom of movement on the piston pin.
Installing the Piston Rings
Figures 12-37 through 12-39
Measure
1 . Ring end gap as follows:
A . Select rings comparable in size to the piston
being used.
B . Slip the compression ring into the cylinder
bore and press it down about 7 mm (0.250 in.)
above ring travel. Make sure the ring is square
with the cylinder wall.
C . Measure the space or gap between the ends
of the ring with a feeler gage.
D . Refer to “Specifications” in the proper Section
for correct gap.
E . If the gap between the ends of the ring is not
as specified, remove the ring and try another
for fit.
Figure 12-37 Measuring Ring End Gap
Inspect
1 . Ring fit as follows:
A . Fit each compression ring to the piston on
which it is going to be used.
Figure 12-38 Checking Ring Fit
B . Slip the outer surface of the top and second
compression ring into the respective piston
ring groove, to make sure that the ring is free.
If binding occurs at any point, the cause
should be determined. If binding is caused by
the ring groove, correct by depressing the
groove with a fine cut file. If the binding is
caused by a distorted ring, try a new ring.
NOTICE:
All compression rings are marked on the
upper side of the ring. When installing the
compression rings, make sure the MARKED SIDE
IS TOWARD THE TOP OF THE PISTON.
NOTICE:
The oil control rings are three piece types,
consisting of two rails and an expander.
Assemble
1 . Expander.
2 . Lower rail.
3 . Upper rail.
4 . Lower compression ring.
5 . Upper compression ring.
• Flex all rings to make sure they are free. If
binding occurs at any point the cause should be
determined. If binding is caused by the ring
groove, correct by dressing the groove with a
fine cut file. If binding is caused by a distorted
ring, try a new ring.
• Ring gaps must be 180° apart.
• Rail gaps must be 180° apart.